Synthesis of terminal alkenes from internal alkenes and ethylene via olefin metathesis

ABSTRACT

This invention relates generally to olefin metathesis, and more particularly relates to the synthesis of terminal alkenes from internal alkenes using a cross-metathesis reaction catalyzed by a selected olefin metathesis catalyst. In one embodiment of the invention, for example, a method is provided for synthesizing a terminal olefin, the method comprising contacting an olefinic substrate comprised of at least one internal olefin with ethylene, in the presence of a metathesis catalyst, wherein the catalyst is present in an amount that is less than about 1000 ppm relative to the olefinic substrate, and wherein the metathesis catalyst has the structure of formula (II) 
     
       
         
         
             
             
         
       
     
     wherein the various substituents are as defined herein. The invention has utility, for example, in the fields of catalysis, organic synthesis, and industrial chemistry.

RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No. 13/965,845, filed Aug. 13, 2013; which is a Continuation of U.S. application Ser. No. 13/913,814, filed Jun. 10, 2013 (now U.S. Pat. No. 9,139,605, issued on Sep. 22, 2015), which is a Divisional of U.S. application Ser. No. 13/234,542, filed Sep. 16, 2011 (now U.S. Pat. No. 8,481,747, issued on Jul. 9, 2013), which is a Divisional of U.S. application Ser. No. 11/879,029, filed Jul. 13, 2007 (now U.S. Pat. No. 8,067,610, issued on Nov. 29, 2011), which claims priority to U.S. Provisional Application No. 60/830,944, filed Jul. 13, 2006, the disclosures of which are incorporated herein by reference.

GOVERNMENT RIGHTS

This invention was made with Government support under grant no. DE-FG36-04G014016 awarded by the Department of Energy. The U.S. Government has certain rights in this invention.

TECHNICAL FIELD

This invention relates generally to olefin metathesis, and more particularly relates to the synthesis of terminal alkenes from internal alkenes using a cross-metathesis reaction catalyzed by a selected olefin metathesis catalyst. The invention has utility in the fields of catalysis, organic synthesis, and industrial chemistry.

BACKGROUND

Ethenolysis is a specific cross metathesis reaction between an internal olefin and ethylene to produce terminal olefins. Scheme 1 demonstrates the ethenolysis reaction:

Examples of ethenolysis include the conversion of a mixture of ethylene and 2-butene into propene (as in the Phillips triolefin process and the Meta-4 process developed by the Institut Francais du Petrole), and the conversion of a mixture of ethylene and 2,4,4-trimethyl-2-pentene into neohexene. These processes typically use heterogeneous ill-defined olefin metathesis catalysts based on tungsten and rhenium oxides and which are not compatible with air, water, oxygenates, and many functional groups. The ethenolysis reaction has also been implemented in the conversion of seed oil-derived substrates such as fatty acid methyl esters (FAME) into terminally unsaturated carboxylic acids (e.g., 9-decenoic acid) and terminal olefins (e.g., 1-decene). The ethenolysis of FAME was originally performed with a heterogeneous, ill-defined rhenium catalyst to give turnover numbers (TON) of about 100. The so-called “first generation” Grubbs catalysts such as Cl₂(PCy₃)₂Ru═CH—CH═CPh₂, Cl₂(PCy₃)₂Ru═CHPh (“C823”), and complexes that contain bicyclic phosphines, as well as first generation Grubbs-Hoveyda catalyst (“C601”), have been used in the ethenolysis of vegetable oil-derived materials. The production of 1-octene from linoleic acid using an enzyme-mediated isomerization reaction, followed by a metathesis reaction using ethylene and various metathesis catalysts, has also been described. However, the conjugation present in these reactants necessitated a high catalyst loading and often resulted in a relatively low yield of terminal olefin products.

It is therefore desirable to provide a convenient and effective route for the production of terminal olefins. Compared with known metathesis methods, an ideal process would: substantially reduce the amount of catalyst that is needed for the cross-metathesis reaction; provide a high degree of selectivity for the preparation of terminal olefins from internal olefins; and allow the use of a mixture of internal olefins from a variety of sources. An ideal process would also not require isomerization of the olefinic substrate prior to the metathesis reaction, and an ideal process would allow for the preparation of terminal olefins directly from seed oils and from the component materials of seed oils, or from non-isomerized derivatives of seed oils.

SUMMARY OF THE DISCLOSURE

Accordingly, the disclosure is directed to addressing one or more of the aforementioned issues, and, in one embodiment, provides a method for synthesizing a terminal olefin. The method comprises contacting an olefinic substrate comprised of at least one internal olefin with ethylene in the presence of a metathesis catalyst. The catalyst is present in an amount that is less than about 1000 ppm relative to the olefinic substrate. The metathesis catalyst has the structure of formula (II)

wherein:

m is zero, 1, or 2;

M is Ru or Os;

n1 and n2 are independently selected from zero and 1;

X¹ and X² are anionic ligands, and may be the same or different;

R¹ and R² are independently selected from H, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl;

L² and L³ are neutral electron donating ligands, and may be the same or different; and

L¹ is a carbene ligand with the structure of formula (IIIa)

wherein:

Z¹ is —N(Ar¹)(R⁹) and Z² is —N(Ar²)(R^(9A)) or —C(R¹⁰)(R¹¹)(R¹²);

Ar¹ and Ar² are independently aryl substituted with at least one group selected from C₂-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl; and

R⁹, R^(9A), R¹⁰, R¹¹, and R¹² are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, provided that any two of X¹, X², L¹, L², L³, R¹, R², R⁹, R^(9A), R¹⁰, R¹¹, and R¹² may be taken together to form a cycle.

In another embodiment, the invention provides a method for synthesizing a terminal olefin. The method comprises contacting, under reaction conditions effective to prepare a terminal olefin, an olefinic substrate comprising a mixture of mono-, di-, and tri-glycerides with ethylene in the presence of a ruthenium alkylidene metathesis catalyst. The catalyst comprises an N-heterocyclic carbene ligand, and the olefinic substrate comprises at least one internal olefin.

In yet another embodiment, the invention provides a method for synthesizing a terminal olefin. The method comprises contacting, under reaction conditions effective to prepare a terminal olefin, an olefinic substrate with ethylene in the presence of a ruthenium alkylidene metathesis catalyst. The olefinic substrate comprises at least one internal olefin, and further comprises a seed oil or a composition derived from a seed oil. The catalyst comprises an N-heterocyclic carbene ligand. At least about 50% of the metathesis reaction products comprise a terminal olefin and at least about 50% of the internal olefins initially present in the reaction mixture are converted into terminal olefins.

In a still further embodiment, the invention provides a method for synthesizing a terminal olefin. The method comprises contacting, in the presence of a metathesis catalyst, an olefinic substrate comprising at least one internal olefin with ethylene. The metathesis catalyst has the structure of formula (IIA)

wherein:

m is 0, 1, or 2;

M is Ru or Os;

n1 and n2 are independently selected from zero and 1;

X^(1A) and X^(2A) are CF₃CO₂;

R¹ and R² are independently selected from H, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl;

L² and L³ are neutral electron donating ligands; and

L^(1A) is an N-heterocyclic carbene ligand.

In a still further embodiment, the invention provides a method for synthesizing a terminal olefin. The method comprises contacting, under reaction conditions effective to prepare a terminal olefin, an olefinic substrate with ethylene, in the presence of a metathesis catalyst. The olefinic substrate comprises at least one internal olefin, and comprises a seed oil or a composition derived from a seed oil. The metathesis catalyst comprises an N-heterocyclic carbene ligand and is present in an amount that is less than about 50 ppm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the results from an etheneolysis reaction of methyl oleate and ethylene.

DETAILED DESCRIPTION OF THE INVENTION Terminology and Definitions

Unless otherwise indicated, the invention is not limited to specific reactants, substituents, catalysts, reaction conditions, or the like, as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

As used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “an α-olefin” includes a single α-olefin as well as a combination or mixture of two or more α-olefin, reference to “a substituent” encompasses a single substituent as well as two or more substituents, and the like.

As used in the specification and the appended claims, the terms “for example,” “for instance,” “such as,” or “including” are meant to introduce examples that further clarify more general subject matter. Unless otherwise specified, these examples are provided only as an aid for understanding the invention, and are not meant to be limiting in any fashion.

In this specification and in the claims that follow, reference will be made to a number of terms, which shall be defined to have the following meanings:

The term “alkyl” as used herein refers to a linear, branched, or cyclic saturated hydrocarbon group typically although not necessarily containing 1 to about 24 carbon atoms, preferably 1 to about 12 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl, and the like, as well as cycloalkyl groups such as cyclopentyl, cyclohexyl and the like. Generally, although again not necessarily, alkyl groups herein contain 1 to about 12 carbon atoms. The term “lower alkyl” intends an alkyl group of 1 to 6 carbon atoms, and the specific term “cycloalkyl” intends a cyclic alkyl group, typically having 4 to 8, preferably 5 to 7, carbon atoms. The term “substituted alkyl” refers to alkyl substituted with one or more substituent groups, and the terms “heteroatom-containing alkyl” and “heteroalkyl” refer to alkyl in which at least one carbon atom is replaced with a heteroatom. If not otherwise indicated, the terms “alkyl” and “lower alkyl” include linear, branched, cyclic, unsubstituted, substituted, and/or heteroatom-containing alkyl and lower alkyl, respectively. If not otherwise indicated, the terms “alkyl” and “lower alkyl” include primary, secondary, and tertiary alkyl and lower alkyl.

The term “alkylene” as used herein refers to a difunctional linear, branched, or cyclic alkyl group, where “alkyl” is as defined above.

The term “alkenyl” as used herein refers to a linear, branched, or cyclic hydrocarbon group of 2 to about 24 carbon atoms containing at least one double bond, such as ethenyl, n-propenyl, isopropenyl, n-butenyl, isobutenyl, octenyl, decenyl, tetradecenyl, hexadecenyl, eicosenyl, tetracosenyl, and the like. Preferred alkenyl groups herein contain 2 to about 12 carbon atoms. The term “lower alkenyl” intends an alkenyl group of 2 to 6 carbon atoms, and the specific term “cycloalkenyl” intends a cyclic alkenyl group, preferably having 5 to 8 carbon atoms. The term “substituted alkenyl” refers to alkenyl substituted with one or more substituent groups, and the terms “heteroatom-containing alkenyl” and “heteroalkenyl” refer to alkenyl in which at least one carbon atom is replaced with a heteroatom. If not otherwise indicated, the terms “alkenyl” and “lower alkenyl” include linear, branched, cyclic, unsubstituted, substituted, and/or heteroatom-containing alkenyl and lower alkenyl, respectively.

The term “alkenylene” as used herein refers to a difunctional linear, branched, or cyclic alkenyl group, where “alkenyl” is as defined above.

The term “alkynyl” as used herein refers to a linear or branched hydrocarbon group of 2 to about 24 carbon atoms containing at least one triple bond, such as ethynyl, n-propynyl, and the like. Preferred alkynyl groups herein contain 2 to about 12 carbon atoms. The term “lower alkynyl” intends an alkynyl group of 2 to 6 carbon atoms. The term “substituted alkynyl” refers to alkynyl substituted with one or more substituent groups, and the terms “heteroatom-containing alkynyl” and “heteroalkynyl” refer to alkynyl in which at least one carbon atom is replaced with a heteroatom. If not otherwise indicated, the terms “alkynyl” and “lower alkynyl” include linear, branched, unsubstituted, substituted, and/or heteroatom-containing alkynyl and lower alkynyl, respectively.

The term “aryl” as used herein, and unless otherwise specified, refers to an aromatic substituent containing a single aromatic ring or multiple aromatic rings that are fused together, directly linked, or indirectly linked (such that the different aromatic rings are bound to a common group such as a methylene or ethylene moiety). Preferred aryl groups contain 5 to 24 carbon atoms, and particularly preferred aryl groups contain 5 to 14 carbon atoms. Exemplary aryl groups contain one aromatic ring or two fused or linked aromatic rings, e.g., phenyl, naphthyl, biphenyl, diphenylether, diphenylamine, benzophenone, and the like. “Substituted aryl” refers to an aryl moiety substituted with one or more substituent groups, and the terms “heteroatom-containing aryl” and “heteroaryl” refer to aryl substituents in which at least one carbon atom is replaced with a heteroatom, as will be described in further detail infra.

The term “alkaryl” refers to an aryl group with an alkyl substituent, and the term “aralkyl” refers to an alkyl group with an aryl substituent, wherein “aryl” and “alkyl” are as defined above. Preferred alkaryl and aralkyl groups contain 6 to 24 carbon atoms, and particularly preferred alkaryl and aralkyl groups contain 6 to 16 carbon atoms. Alkaryl groups include, for example, p-methylphenyl, 2,4-dimethylphenyl, p-cyclohexylphenyl, 2,7-dimethylnaphthyl, 7-cyclooctylnaphthyl, 3-ethyl-cyclopenta-1,4-diene, and the like. Examples of aralkyl groups include, without limitation, benzyl, 2-phenyl-ethyl, 3-phenyl-propyl, 4-phenyl-butyl, 5-phenyl-pentyl, 4-phenylcyclohexyl, 4-benzylcyclohexyl, 4-phenylcyclohexylmethyl, 4-benzylcyclohexylmethyl, and the like. The terms “alkaryloxy” and “aralkyloxy” refer to substituents of the formula —OR wherein R is alkaryl or aralkyl, respectively, as just defined.

The term “acyl” refers to substituents having the formula —(CO)-alkyl, —(CO)-aryl, or —(CO)-aralkyl, and the term “acyloxy” refers to substituents having the formula —O(CO)-alkyl, —O(CO)-aryl, or —O(CO)-aralkyl, wherein “alkyl,” “aryl, and “aralkyl” are as defined above.

The terms “cyclic” and “ring” refer to alicyclic or aromatic groups that may or may not be substituted and/or heteroatom containing, and that may be monocyclic, bicyclic, or polycyclic. The term “alicyclic” is used in the conventional sense to refer to an aliphatic cyclic moiety, as opposed to an aromatic cyclic moiety, and may be monocyclic, bicyclic or polycyclic.

The terms “halo” and “halogen” are used in the conventional sense to refer to a chloro, bromo, fluoro or iodo substituent.

“Hydrocarbyl” refers to univalent hydrocarbyl radicals containing 1 to about 30 carbon atoms, preferably 1 to about 24 carbon atoms, most preferably 1 to about 12 carbon atoms, including linear, branched, cyclic, saturated and unsaturated species, such as alkyl groups, alkenyl groups, aryl groups, and the like. The term “lower hydrocarbyl” intends a hydrocarbyl group of 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, and the term “hydrocarbylene” intends a divalent hydrocarbyl moiety containing 1 to about 30 carbon atoms, preferably 1 to about 24 carbon atoms, most preferably 1 to about 12 carbon atoms, including linear, branched, cyclic, saturated and unsaturated species. The term “lower hydrocarbylene” intends a hydrocarbylene group of 1 to 6 carbon atoms. “Substituted hydrocarbyl” refers to hydrocarbyl substituted with one or more substituent groups, and the terms “heteroatom-containing hydrocarbyl” and “heterohydrocarbyl” refer to hydrocarbyl in which at least one carbon atom is replaced with a heteroatom. Similarly, “substituted hydrocarbylene” refers to hydrocarbylene substituted with one or more substituent groups, and the terms “heteroatom-containing hydrocarbylene” and heterohydrocarbylene” refer to hydrocarbylene in which at least one carbon atom is replaced with a heteroatom. Unless otherwise indicated, the term “hydrocarbyl” and “hydrocarbylene” are to be interpreted as including substituted and/or heteroatom-containing hydrocarbyl and hydrocarbylene moieties, respectively.

The term “heteroatom-containing” as in a “heteroatom-containing hydrocarbyl group” refers to a hydrocarbon molecule or a hydrocarbyl molecular fragment in which one or more carbon atoms is replaced with an atom other than carbon, e.g., nitrogen, oxygen, sulfur, phosphorus or silicon, typically nitrogen, oxygen or sulfur. Similarly, the term “heteroalkyl” refers to an alkyl substituent that is heteroatom-containing, the term “heterocyclic” refers to a cyclic substituent that is heteroatom-containing, the terms “heteroaryl” and “heteroaromatic” respectively refer to “aryl” and “aromatic” substituents that are heteroatom-containing, and the like. It should be noted that a “heterocyclic” group or compound may or may not be aromatic, and further that “heterocycles” may be monocyclic, bicyclic, or polycyclic as described above with respect to the term “aryl.” Examples of heteroalkyl groups include alkoxyaryl, alkylsulfanyl-substituted alkyl, N-alkylated amino alkyl, and the like. Examples of heteroaryl substituents include pyrrolyl, pyrrolidinyl, pyridinyl, quinolinyl, indolyl, pyrimidinyl, imidazolyl, 1,2,4-triazolyl, tetrazolyl, etc., and examples of heteroatom-containing alicyclic groups are pyrrolidino, morpholino, piperazino, piperidino, etc.

By “substituted” as in “substituted hydrocarbyl,” “substituted alkyl,” “substituted aryl,” and the like, as alluded to in some of the aforementioned definitions, is meant that in the hydrocarbyl, alkyl, aryl, or other moiety, at least one hydrogen atom bound to a carbon (or other) atom is replaced with one or more non-hydrogen substituents. Examples of such substituents include, without limitation: functional groups referred to herein as “Fn,” such as halo, hydroxyl, sulfhydryl, C₁-C₂₄ alkoxy, C₂-C₂₄ alkenyloxy, C₂-C₂₄ alkynyloxy, C₅-C₂₄ aryloxy, C₆-C₂₄ aralkyloxy, C₆-C₂₄ alkaryloxy, acyl (including C₂-C₂₄ alkylcarbonyl (—CO-alkyl) and C₆-C₂₄ arylcarbonyl (—CO-aryl)), acyloxy (—O-acyl, including C₂-C₂₄ alkylcarbonyloxy (—O—CO-alkyl) and C₆-C₂₄ arylcarbonyloxy (—O—CO-aryl)), C₂-C₂₄ alkoxycarbonyl (—(CO)—O-alkyl), C₆-C₂₄ aryloxycarbonyl (—(CO)—O-aryl), halocarbonyl (—CO)—X where X is halo), C₂-C₂₄ alkylcarbonato (—O—(CO)—O-alkyl), C₆-C₂₄ arylcarbonato (—O—(CO)—O-aryl), carboxy (—COOH), carboxylato (—COO—), carbamoyl (—(CO)—NH₂), mono-(C₁-C₂₄ alkyl)-substituted carbamoyl (—(CO)—NH(C₁-C₂₄ alkyl)), di-(C₁-C₂₄ alkyl)-substituted carbamoyl (—(CO)—N(C₁-C₂₄ alkyl)₂), mono-(C₅-C₂₄ aryl)-substituted carbamoyl (—(CO)—NH-aryl), di-(C₅-C₂₄ aryl)-substituted carbamoyl (—(CO)—N(C₅-C₂₄ aryl)₂), di-N—(C₁-C₂₄ alkyl), N—(C₅-C₂₄ aryl)-substituted carbamoyl, thiocarbamoyl (—(CS)—NH₂), mono-(C₁-C₂₄ alkyl)-substituted thiocarbamoyl (—(CO)—NH(C₁-C₂₄ alkyl)), di-(C₁-C₂₄ alkyl)-substituted thiocarbamoyl (—(CO)—N(C₁-C₂₄ alkyl)₂), mono-(C₅-C₂₄ aryl)-substituted thiocarbamoyl (—(CO)—NH-aryl), di-(C₅-C₂₄ aryl)-substituted thiocarbamoyl (—(CO)—N(C₅-C₂₄ aryl)₂), di-N—(C₁-C₂₄ alkyl), N—(C₅-C₂₄ aryl)-substituted thiocarbamoyl, carbamido (—NH—(CO)—NH₂), cyano(—C≡N), cyanato (—O—C≡N), thiocyanato (—S—C≡N), formyl (—(CO)—H), thioformyl (—(CS)—H), amino (—NH₂), mono-(C₁-C₂₄ alkyl)-substituted amino, di-(C₁-C₂₄ alkyl)-substituted amino, mono-(C₅-C₂₄ aryl)-substituted amino, di-(C₅-C₂₄ aryl)-substituted amino, C₂-C₂₄ alkylamido (—NH—(CO)-alkyl), C₆-C₂₄ arylamido (—NH—(CO)-aryl), imino (—CR═NH where R=hydrogen, C₁-C₂₄ alkyl, C₅-C₂₄ aryl, C₆-C₂₄ alkaryl, C₆-C₂₄ aralkyl, etc.), C₂-C₂₀ alkylimino (—CR═N(alkyl), where R=hydrogen, C₁-C₂₄ alkyl, C₅-C₂₄ aryl, C₆-C₂₄ alkaryl, C₆-C₂₄ aralkyl, etc.), arylimino (—CR═N(aryl), where R=hydrogen, C₁-C₂₀ alkyl, C₅-C₂₄ aryl, C₆-C₂₄ alkaryl, C₆-C₂₄ aralkyl, etc.), nitro (—NO₂), nitroso (—NO), sulfo (—SO₂—OH), sulfonato (—SO₂—O—), C₁-C₂₄ alkylsulfanyl (—S-alkyl; also termed “alkylthio”), C₅-C₂₄ arylsulfanyl (—S-aryl; also termed “arylthio”), C₁-C₂₄ alkylsulfinyl (—(SO)-alkyl), C₅-C₂₄ arylsulfinyl (—(SO)-aryl), C₁-C₂₄ alkylsulfonyl (—SO₂-alkyl), C₅-C₂₄ arylsulfonyl (—SO₂-aryl), boryl (—BH₂), borono (—B(OH)₂), boronato (—B(OR)₂ where R is alkyl or other hydrocarbyl), phosphono (—P(O)(OH)₂), phosphonato (—P(O)(O)₂), phosphinato (—P(O)(O)), phospho (—PO₂), phosphino (—PH₂), silyl (—SiR₃ wherein R is hydrogen or hydrocarbyl), and silyloxy (—O-silyl); and the hydrocarbyl moieties C₁-C₂₄ alkyl (preferably C₁-C₁₂ alkyl, more preferably C₁-C₆ alkyl), C₂-C₂₄ alkenyl (preferably C₂-C₁₂ alkenyl, more preferably C₂-C₆ alkenyl), C₂-C₂₄ alkynyl (preferably C₂-C₁₂ alkynyl, more preferably C₂-C₆ alkynyl), C₅-C₂₄ aryl (preferably C₅-C₁₄ aryl), C₆-C₂₄ alkaryl (preferably C₆-C₁₆ alkaryl), and C₆-C₂₄ aralkyl (preferably C₆-C₁₆ aralkyl).

In addition, the aforementioned functional groups may, if a particular group permits, be further substituted with one or more additional functional groups or with one or more hydrocarbyl moieties such as those specifically enumerated above. Analogously, the above-mentioned hydrocarbyl moieties may be further substituted with one or more functional groups or additional hydrocarbyl moieties such as those specifically enumerated.

“Optional” or “optionally” means that the subsequently described circumstance may or may not occur, so that the description includes instances where the circumstance occurs and instances where it does not. For example, the phrase “optionally substituted” means that a non-hydrogen substituent may or may not be present on a given atom, and, thus, the description includes structures wherein a non-hydrogen substituent is present and structures wherein a non-hydrogen substituent is not present.

Methods and Compositions:

Accordingly, the invention provides an olefin cross-metathesis method for synthesizing a terminal olefin from ethylene and an olefinic substrate comprised of at least one internal olefin. The reactions are carried out catalytically, in the presence of a ruthenium alkylidene metathesis catalyst.

In a first embodiment of the invention, then, the olefin metathesis reaction is carried out by contacting the at least one internal olefin with ethylene in the presence of the metathesis catalyst under reaction conditions effective to allow cross-metathesis to occur.

The olefin metathesis catalyst for carrying out the cross-metathesis reactions of the invention is preferably a Group 8 transition metal complex having the structure of formula (II)

wherein:

m is zero, 1, or 2;

M is Ru or Os;

n1 and n2 are independently selected from zero and 1;

X¹ and X² are anionic ligands and may be the same or different;

R¹ and R² are independently selected from H, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl;

L² and L³ are neutral electron donating ligands and may be the same or different; and

L¹ is a carbene ligand with the structure of formula (IIIa)

wherein:

Z¹ is —N(Ar¹)(R⁹) and Z² is —N(Ar²)(R^(9A)) or —C(R¹⁰)(R¹¹)(R¹²);

Ar¹ and Ar² are independently aryl substituted with at least one group selected from C₂-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl; and

R⁹, R^(9A), R¹⁰, R¹¹, and R¹² are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl,

wherein any two of X¹, X², L¹, L², L³, R¹, R², R⁹, R^(9A), R¹⁰, R¹¹, and R¹² may be taken together to form a cycle.

Preferred catalysts contain Ru or Os as the Group 8 transition metal, with Ru particularly preferred.

Numerous embodiments of the catalysts useful in the reactions of the invention are described in more detail infra. For the sake of convenience, the catalysts are described in groups, but it should be emphasized that these groups are not meant to be limiting in any way. That is, any of the catalysts useful in the invention may fit the description of more than one of the groups described herein.

A first group of catalysts having the structure of formula (II) is commonly referred to as Second Generation Grubbs-type catalysts. For catalysts of the first group, M, n1, n2, and m are as described above, and X¹, X², L¹, L², L³, R¹, and R² are further described as follows.

L² is selected from phosphine, sulfonated phosphine, phosphite, phosphinite, phosphonite, arsine, stibine, ether, amine, amide, imine, sulfoxide, carboxyl, nitrosyl, pyridine, substituted pyridine, imidazole, substituted imidazole, pyrazine, and thioether. Exemplary ligands are trisubstituted phosphines.

X¹ and X² are anionic ligands, and may be the same or different, or are linked together to form a cyclic group, typically although not necessarily a five- to eight-membered ring. In preferred embodiments, X¹ and X² are each independently hydrogen, halide, or one of the following groups: C₁-C₂₀ alkyl, C₅-C₂₄ aryl, C₁-C₂₀ alkoxy, C₅-C₂₄ aryloxy, C₂-C₂₀ alkoxycarbonyl, C₆-C₂₄ aryloxycarbonyl, C₂-C₂₄ acyl, C₂-C₂₄ acyloxy, C₁-C₂₀ alkylsulfonato, C₅-C₂₄ arylsulfonato, C₁-C₂₀ alkylsulfanyl, C₅-C₂₄ arylsulfanyl, C₁-C₂₀ alkylsulfinyl, or C₅-C₂₄ arylsulfinyl. Optionally, X¹ and X² may be substituted with one or more moieties selected from C₁-C₁₂ alkyl, C₁-C₁₂ alkoxy, C₅-C₂₄ aryl, and halide, which may, in turn, with the exception of halide, be further substituted with one or more groups selected from halide, C₁-C₆ alkyl, C₁-C₆ alkoxy, and phenyl. In more preferred embodiments, X¹ and X² are halide, benzoate, C₂-C₆ acyl, C₂-C₆ alkoxycarbonyl, C₁-C₆ alkyl, phenoxy, C₁-C₆ alkoxy, C₁-C₆ alkylsulfanyl, aryl, or C₁-C₆ alkylsulfonyl. In even more preferred embodiments, X¹ and X² are each halide, CF₃CO₂, CH₃CO₂, CFH₂CO₂, (CH₃)₃CO, (CF₃)₂(CH₃)CO, (CF₃)(CH₃)₂CO, PhO, MeO, EtO, tosylate, mesylate, or trifluoromethane-sulfonate.

R¹ and R² are independently selected from hydrogen, hydrocarbyl (e.g., C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl, C₅-C₂₄ aryl, C₆-C₂₄ alkaryl, C₆-C₂₄ aralkyl, etc.), substituted hydrocarbyl (e.g., substituted C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl, C₅-C₂₄ aryl, C₆-C₂₄ alkaryl, C₆-C₂₄ aralkyl, etc.), heteroatom-containing hydrocarbyl (e.g., heteroatom-containing C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl, C₅-C₂₄ aryl, C₆-C₂₄ alkaryl, C₆-C₂₄ aralkyl, etc.), and substituted heteroatom-containing hydrocarbyl (e.g., substituted heteroatom-containing C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl, C₅-C₂₄ aryl, C₆-C₂₄ alkaryl, C₆-C₂₄ aralkyl, etc.), and functional groups. R¹ and R² may also be linked to form a cyclic group, which may be aliphatic or aromatic, and may contain substituents and/or heteroatoms. Generally, such a cyclic group will contain 4 to 12, preferably 5, 6, 7, or 8 ring atoms.

In preferred catalysts, R¹ is hydrogen and R² is selected from C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, and C₅-C₂₄ aryl, more preferably C₁-C₆ alkyl, C₂-C₆ alkenyl, and C₅-C₁₄ aryl. Still more preferably, R² is phenyl, vinyl, methyl, isopropyl, or t-butyl, optionally substituted with one or more moieties selected from C₁-C₆ alkyl, C₁-C₆ alkoxy, phenyl, and a functional group Fn as defined earlier herein. Most preferably, R² is phenyl or vinyl substituted with one or more moieties selected from methyl, ethyl, chloro, bromo, iodo, fluoro, nitro, dimethylamino, methyl, methoxy, and phenyl. Optimally, R² is phenyl or —C═C(CH₃)₂.

Any two or more (typically two, three, or four) of X¹, X², L¹, L², L³, R¹, and R² can be taken together to form a cyclic group. When any of X¹, X², L¹, L², L³, R¹, and R² are linked to form cyclic groups, those cyclic groups may contain 4 to 12, preferably 4, 5, 6, 7 or 8 atoms, or may comprise two or three of such rings, which may be either fused or linked. The cyclic groups may be aliphatic or aromatic, and may be heteroatom-containing and/or substituted. The cyclic group may, in some cases, form a bidentate ligand or a tridentate ligand. Examples of bidentate ligands include, but are not limited to, bisphosphines, dialkoxides, alkyldiketonates, and aryldiketonates.

L¹ is a carbene ligand with the structure of formula (IIIa)

(IIIa)

wherein Z¹ is —N(Ar¹)(R⁹) and Z² is —N(Ar²)(R^(9A)) or —C(R¹⁰)(R¹¹)(R¹²). Ar¹ and Ar² are aryl substituted with at least one group selected from C₂-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl, and Ar¹ and Ar² may be the same or different. R⁹, R^(9A), R¹⁰, R¹¹, and R¹² are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl. Furthermore, any two of X¹, X², L¹, L², L³, R¹, R², R⁹, R^(9A), R¹⁰, R¹¹, and R¹² may be taken together to form a cycle.

For example, Z¹ is —N(Ar¹)(R⁹), Z² is —C(R¹⁰)(R¹¹)(R¹²), and R⁹ and R¹² are linked. The linkage formed by R⁹ and R¹² has the structure

such that L¹ has the structure of formula (IIIb)

wherein α is an optional double bond, and R¹³, R¹⁴, R¹⁵, and R¹⁶ are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, provided that R¹⁴ and R¹⁶ are not present if α is present, and provided that any two or more of Ar¹, R¹⁰, R¹¹, R¹³, R¹⁴, R¹⁵, and R¹⁶ may be taken together to form a cyclic group. For example, R¹⁰ and R¹¹ are taken together to form a cyclic group, such as a six-membered cyclic group.

In a preferred embodiment, Ar¹ has the structure of formula (VIIa)

wherein

represents the attachment point to N in formula (IIIb), R¹⁷ and R¹⁸ are independently selected from C₂-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl, and R¹⁹, R²⁰, and R²¹ are independently selected from H, C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl. For example, R¹⁹, R²⁰, and R²¹ are H such that Ar¹ has the structure of formula (VIIb)

wherein the wavy line represents the attachment point to N in formula (IIIb) and R¹⁷ and R¹⁸ are independently selected from C₂-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl. In a more preferred embodiment, R¹⁷ and R¹⁸ are independently C₂-C₁₂ alkyl; for example, R¹⁷ and R¹⁸ are both ethyl.

As another example, Z¹ is —N(Ar¹)(R⁹) and Z² is —N(Ar²)(R^(9A)). In a preferred embodiment, R⁹ and R^(9A) are linked such that L¹ has the structure of formula (IIIc)

wherein α is an optional double bond, Ar² is aryl substituted with at least one group selected from C₂-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl, and R¹³, R¹⁴, R¹⁵, and R¹⁶ are as described previously. In a preferred embodiment, L¹ has the formula of (IIId)

wherein R²², R²³, R²⁷ and R²⁸ are independently selected from C₂-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl, and R²⁴, R²⁵, R²⁶, R²⁹, R³⁰, and R³¹ are independently selected from H, C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl. For example, a is not present, and L¹ has the structure of formula (IIId-1)

As a further example, a is not present, and R¹³, R¹⁴, R¹⁵, R¹⁶, R²⁴, R²⁵, R²⁶, R²⁹, R³⁰, and R³¹ are each H such that L¹ has the structure of formula (IIIe)

wherein R²², R²³, R²⁷, and R²⁸ are independently selected from C₂-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl. As a further example, R²², R²³, R²⁷, and R²⁸ are each independently C₃-C₁₂ secondary alky or C₄-C₁₂ tertiary alkyl, and as a still further example, R²², R²³, R²⁷, and R²⁸ are isopropyl.

Examples of N-heterocyclic carbene ligands suitable as L¹ also include the following:

In a second group of catalysts having the structure of formula (II), M, m, n, X¹, X², L¹, R¹, and R² are as defined for the first group of catalysts having the structure of formula (II), and L² and L³ are weakly coordinating neutral electron donor ligands in the form of optionally substituted heterocyclic groups. Again, n is zero or 1, such that L³ may or may not be present. Generally, in the second group of catalysts, L² and L³ are optionally substituted five- or six-membered monocyclic groups containing 1 to 4, preferably 1 to 3, most preferably 1 to 2 heteroatoms, or are optionally substituted bicyclic or polycyclic structures composed of 2 to 5 such five- or six-membered monocyclic groups. If the heterocyclic group is substituted, it should not be substituted on a coordinating heteroatom, and any one cyclic moiety within a heterocyclic group will generally not be substituted with more than 3 substituents.

Examples of L² and L³ include, without limitation, heterocycles containing nitrogen, sulfur, oxygen, or a mixture thereof.

Examples of nitrogen-containing heterocycles appropriate for L² and L³ include pyridine, bipyridine, pyridazine, pyrimidine, bipyridamine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, pyrrole, 2H-pyrrole, 3H-pyrrole, pyrazole, 2H-imidazole, 1,2,3-triazole, 1,2,4-triazole, indole, 3H-indole, 1H-isoindole, cyclopenta(b)pyridine, indazole, quinoline, bisquinoline, isoquinoline, bisisoquinoline, cinnoline, quinazoline, naphthyridine, piperidine, piperazine, pyrrolidine, pyrazolidine, quinuclidine, imidazolidine, picolylimine, purine, benzimidazole, bisimidazole, phenazine, acridine, and carbazole.

Examples of sulfur-containing heterocycles appropriate for L² and L³ include thiophene, 1,2-dithiole, 1,3-dithiole, thiepin, benzo(b)thiophene, benzo(c)thiophene, thionaphthene, dibenzothiophene, 2H-thiopyran, 4H-thiopyran, and thioanthrene.

Examples of oxygen-containing heterocycles appropriate for L² and L³ include 2H-pyran, 4H-pyran, 2-pyrone, 4-pyrone, 1,2-dioxin, 1,3-dioxin, oxepin, furan, 2H-1-benzopyran, coumarin, coumarone, chromene, chroman-4-one, isochromen-1-one, isochromen-3-one, xanthene, tetrahydrofuran, 1,4-dioxan, and dibenzofuran.

Examples of mixed heterocycles appropriate for L² and L³ include isoxazole, oxazole, thiazole, isothiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,3,4-oxadiazole, 1,2,3,4-oxatriazole, 1,2,3,5-oxatriazole, 3H-1,2,3-dioxazole, 3H-1,2-oxathiole, 1,3-oxathiole, 4H-1,2-oxazine, 2H-1,3-oxazine, 1,4-oxazine, 1,2,5-oxathiazine, o-isooxazine, phenoxazine, phenothiazine, pyrano[3,4-b]pyrrole, indoxazine, benzoxazole, anthranil, and morpholine.

Preferred L² and L³ ligands are aromatic nitrogen-containing and oxygen-containing heterocycles, and particularly preferred L² and L³ ligands are monocyclic N-heteroaryl ligands that are optionally substituted with 1 to 3, preferably 1 or 2, substituents. Specific examples of particularly preferred L² and L³ ligands are pyridine and substituted pyridines, such as 3-bromopyridine, 4-bromopyridine, 3,5-dibromopyridine, 2,4,6-tribromopyridine, 2,6-dibromopyridine, 3-chloropyridine, 4-chloropyridine, 3,5-dichloropyridine, 2,4,6-trichloropyridine, 2,6-dichloropyridine, 4-iodopyridine, 3,5-diiodopyridine, 3,5-dibromo-4-methylpyridine, 3,5-dichloro-4-methylpyridine, 3,5-dimethyl-4-bromopyridine, 3,5-dimethylpyridine, 4-methylpyridine, 3,5-diisopropylpyridine, 2,4,6-trimethylpyridine, 2,4,6-triisopropylpyridine, 4-(tert-butyl)pyridine, 4-phenylpyridine, 3,5-diphenylpyridine, 3,5-dichloro-4-phenylpyridine, and the like.

In general, any substituents present on L² and/or L³ are selected from halo, C₁-C₂₀ alkyl, substituted C₁-C₂₀ alkyl, C₁-C₂₀ heteroalkyl, substituted C₁-C₂₀ heteroalkyl, C₅-C₂₄ aryl, substituted C₅-C₂₄ aryl, C₅-C₂₄ heteroaryl, substituted C₅-C₂₄ heteroaryl, C₆-C₂₄ alkaryl, substituted C₆-C₂₄ alkaryl, C₆-C₂₄ heteroalkaryl, substituted C₆-C₂₄ heteroalkaryl, C₆-C₂₄ aralkyl, substituted C₆-C₂₄ aralkyl, C₆-C₂₄ heteroaralkyl, substituted C₆-C₂₄ heteroaralkyl, and functional groups, with suitable functional groups including, without limitation, C₁-C₂₀ alkoxy, C₅-C₂₄ aryloxy, C₂-C₂₀ alkylcarbonyl, C₆-C₂₄ arylcarbonyl, C₂-C₂₀ alkylcarbonyloxy, C₆-C₂₄ arylcarbonyloxy, C₂-C₂₀ alkoxycarbonyl, C₆-C₂₄ aryloxycarbonyl, halocarbonyl, C₂-C₂₀ alkylcarbonato, C₆-C₂₄ arylcarbonato, carboxy, carboxylato, carbamoyl, mono-(C₁-C₂₀ alkyl)-substituted carbamoyl, di-(C₁-C₂₀ alkyl)-substituted carbamoyl, di-N—(C₁-C₂₀ alkyl), N—(C₅-C₂₄ aryl)-substituted carbamoyl, mono-(C₅-C₂₄ aryl)-substituted carbamoyl, di-(C₆-C₂₄ aryl)-substituted carbamoyl, thiocarbamoyl, mono-(C₁-C₂₀ alkyl)-substituted thiocarbamoyl, di-(C₁-C₂₀ alkyl)-substituted thiocarbamoyl, di-N—(C₁-C₂₀ alkyl)-N—(C₆-C₂₄ aryl)-substituted thiocarbamoyl, mono-(C₆-C₂₄ aryl)-substituted thiocarbamoyl, di-(C₆-C₂₄ aryl)-substituted thiocarbamoyl, carbamido, formyl, thioformyl, amino, mono-(C₁-C₂₀ alkyl)-substituted amino, di-(C₁-C₂₀ alkyl)-substituted amino, mono-(C₅-C₂₄ aryl)-substituted amino, di-(C₅-C₂₄ aryl)-substituted amino, di-N—(C₁-C₂₀ alkyl), N—(C₅-C₂₄ aryl)-substituted amino, C₂-C₂₀ alkylamido, C₆-C₂₄ arylamido, imino, C₁-C₂₀ alkylimino, C₅-C₂₄ arylimino, nitro, and nitroso. In addition, two adjacent substituents may be taken together to form a ring, generally a five- or six-membered alicyclic or aryl ring, optionally containing 1 to 3 heteroatoms and 1 to 3 substituents as above.

Preferred substituents on L² and L³ include, without limitation, halo, C₁-C₁₂ alkyl, substituted C₁-C₁₂ alkyl, C₁-C₁₂ heteroalkyl, substituted C₁-C₁₂ heteroalkyl, C₅-C₁₄ aryl, substituted C₅-C₁₄ aryl, C₅-C₁₄ heteroaryl, substituted C₅-C₁₄ heteroaryl, C₆-C₁₆ alkaryl, substituted C₆-C₁₆ alkaryl, C₆-C₁₆ heteroalkaryl, substituted C₆-C₁₆ heteroalkaryl, C₆-C₁₆ aralkyl, substituted C₆-C₁₆ aralkyl, C₆-C₁₆ heteroaralkyl, substituted C₆-C₁₆ heteroaralkyl, C₁-C₁₂ alkoxy, C₅-C₁₄ aryloxy, C₂-C₁₂ alkylcarbonyl, C₆-C₁₄ arylcarbonyl, C₂-C₁₂ alkylcarbonyloxy, C₆-C₁₄ arylcarbonyloxy, C₂-C₁₂ alkoxycarbonyl, C₆-C₁₄ aryloxycarbonyl, halocarbonyl, formyl, amino, mono-(C₁-C₁₂ alkyl)-substituted amino, di-(C₁-C₁₂ alkyl)-substituted amino, mono-(C₅-C₁₄ aryl)-substituted amino, di-(C₅-C₁₄ aryl)-substituted amino, and nitro.

Of the foregoing, the most preferred substituents are halo, C₁-C₆ alkyl, C₁-C₆ haloalkyl, C₁-C₆ alkoxy, phenyl, substituted phenyl, formyl, N,N-diC₁—C₆ alkyl)amino, nitro, and nitrogen heterocycles as described above (including, for example, pyrrolidine, piperidine, piperazine, pyrazine, pyrimidine, pyridine, pyridazine, etc.).

L² and L³ may also be taken together to form a bidentate or multidentate ligand containing two or more, generally two, coordinating heteroatoms such as N, O, S, or P, with preferred such ligands being diimine ligands of the Brookhart type. One representative bidentate ligand has the structure of formula (VIII)

wherein R³², R³³, R³⁴, and R³⁵ are independently hydrocarbyl (e.g., C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl, C₅-C₂₄ aryl, C₆-C₂₄ alkaryl, or C₆-C₂₄ aralkyl), substituted hydrocarbyl (e.g., substituted C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl, C₅-C₂₄ aryl, C₆-C₂₄ alkaryl, or C₆-C₂₄ aralkyl), heteroatom-containing hydrocarbyl (e.g., C₁-C₂₀ heteroalkyl, C₅-C₂₄ heteroaryl, heteroatom-containing C₆-C₂₄ aralkyl, or heteroatom-containing C₆-C₂₄ alkaryl), or substituted heteroatom-containing hydrocarbyl (e.g., substituted C₁-C₂₀ heteroalkyl, C₅-C₂₄ heteroaryl, heteroatom-containing C₆-C₂₄ aralkyl, or heteroatom-containing C₆-C₂₄ alkaryl), or (1) R³² and R³³, (2) R³⁴ and R³⁵, (3) R³³ and R³⁴, or (4) both R³² and R³³, and R³⁴ and R³⁵, may be taken together to form a ring, i.e., an N-heterocycle. Preferred cyclic groups in such a case are five- and six-membered rings, typically aromatic rings.

A third group of catalysts having the structure of formula (II), includes catalysts wherein M, n1, n2, m, X¹, X², R¹, R², L¹, L², and L³ are as defined for any of the previously defined catalysts, and two of the substituents are taken together to form a bidentate ligand or a tridentate ligand.

Examples of bidentate ligands include, but are not limited to, bisphosphines, dialkoxides, alkyldiketonates, and aryldiketonates. Specific examples include —P(Ph)₂CH₂CH₂P(Ph)₂-, —As(Ph)₂CH₂CH₂As(Ph₂)-, —P(Ph)₂CH₂CH₂C(CF₃)₂₀—, binaphtholate dianions, pinacolate dianions, —P(CH₃)₂(CH₂)₂P(CH₃)₂—, and —OC(CH₃)₂(CH₃)₂CO—. Preferred bidentate ligands are —P(Ph)₂ CH₂CH₂P(Ph)₂- and —P(CH₃)₂(CH₂)₂P(CH₃)₂—. Tridentate ligands include, but are not limited to, (CH₃)₂ NCH₂CH₂P(Ph)CH₂CH₂N(CH₃)₂. Other preferred tridentate ligands are those in which any three of X¹, X², L¹, L², L³, R¹, and R² (e.g., X¹, L¹, and L²) are taken together to be cyclopentadienyl, indenyl, or fluorenyl, each optionally substituted with C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl, C₁-C₂₀ alkyl, C₅-C₂₀ aryl, C₁-C₂₀ alkoxy, C₂-C₂₀ alkenyloxy, C₂-C₂₀ alkynyloxy, C₅-C₂₀ aryloxy, C₂-C₂₀ alkoxycarbonyl, C₁-C₂₀ alkylthio, C₁-C₂₀ alkylsulfonyl, or C₁-C₂₀ alkylsulfinyl, each of which may be further substituted with C₁-C₆ alkyl, halide, C₁-C₆ alkoxy or with a phenyl group optionally substituted with halide, C₁-C₆ alkyl, or C₁-C₆ alkoxy. More preferably, in compounds of this type, X, L¹, and L² are taken together to be cyclopentadienyl or indenyl, each optionally substituted with vinyl, C₁-C₁₀ alkyl, C₅-C₂₀ aryl, C₁-C₁₀ carboxylate, C₂-C₁₀ alkoxycarbonyl, C₁-C₁₀ alkoxy, or C₅-C₂₀ aryloxy, each optionally substituted with C₁-C₆ alkyl, halide, C₁-C₆ alkoxy or with a phenyl group optionally substituted with halide, C₁-C₆ alkyl or C₁-C₆ alkoxy. Most preferably, X, L¹ and L² may be taken together to be cyclopentadienyl, optionally substituted with vinyl, hydrogen, methyl, or phenyl. Tetradentate ligands include, but are not limited to O₂C(CH₂)₂P(Ph)(CH₂)₂P(Ph)(CH₂)₂CO₂, phthalocyanines, and porphyrins.

For example, m is zero, and L² and R² are taken together to form a cycle. Catalysts of this type are commonly called “Grubbs-Hoveyda” catalysts, and have the structure of formula (IIa)

wherein Q is selected from hydrocarbylene, substituted hydrocarbylene, heteroatom-containing hydrocarbylene, and substituted heteroatom-containing hydrocarbylene, wherein two or more substituents on adjacent atoms within Q may also be taken together to form an additional, optionally substituted cyclic structure. For example, Grubbs-Hoveyda catalysts may have the structure of formula (IIb)

Further examples of Grubbs-Hoveyda-type catalysts include the following:

wherein L¹, X¹, X², and M are as described for any of the other groups of catalysts.

In addition to the catalysts that have the structure of formula (II), as described above, other transition metal carbene complexes may be used in the reactions disclosed herein, including:

neutral ruthenium or osmium metal carbene complexes containing metal centers that are formally in the +2 oxidation state, have an electron count of 16, are penta-coordinated, and are of the general formula (IX);

neutral ruthenium or osmium metal carbene complexes containing metal centers that are formally in the +2 oxidation state, have an electron count of 18, are hexacoordinated, and are of the general formula (X)

cationic ruthenium or osmium metal carbene complexes containing metal centers that are formally in the +2 oxidation state, have an electron count of 14, are tetracoordinated, and are of the general formula (XI); and

cationic ruthenium or osmium metal carbene complexes containing metal centers that are formally in the +2 oxidation state, have an electron count of 14, are penta-coordinated, and are of the general formula (XII)

wherein: X¹, X², L¹, L², n, L³, R¹, and R² are as defined for any of the previously defined four groups of catalysts; r and s are independently zero or 1; t is an integer in the range of zero to 5; Y is any non-coordinating anion (e.g., a halide ion, BF₄—, etc.); Z¹ and Z² are independently selected from —O—, —S—, —NR₂—, —PR²—, —P(═O)R², —P(OR²)—, —P(═O)(OR²)—, —C(═O)—, —C(═O)O—, —OC(═O)—, —OC(═O)O—, —S(═O)—, and —S(═O)₂—; Z³ is any cationic moiety such as —P(R²)₃, or —N(R²)₃; and any two or more of X¹, X², L¹, L², L³, n, Z¹, Z², Z³, R¹, and R² may be taken together to form a cyclic group, e.g., a multidentate ligand, and wherein any one or more of X¹, X², L¹, L², n, L³, Z¹, Z², Z³, R¹, and R² may be attached to a support.

As is understood in the field of catalysis, suitable solid supports for any of the catalysts described herein may be of synthetic, semi-synthetic, or naturally occurring materials, which may be organic or inorganic, e.g., polymeric, ceramic, or metallic. Attachment to the support will generally, although not necessarily, be covalent, and the covalent linkage may be direct or indirect, if indirect, typically through a functional group on a support surface.

Non-limiting examples of catalysts that may be used in the reactions of the invention include the following, which for convenience are identified throughout this disclosure by reference to their molecular weight:

In the foregoing molecular structures and formulae, Ph represents phenyl, Cy represents cyclohexyl, i-Pr represents isopropyl, Et represents ethyl, t-Bu represents tertiary butyl, and py represents pyridine (coordinated through the N atom).

Further examples of catalysts useful in the reactions of the invention include the following: ruthenium (II) [1,3-bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro (phenylmethylene) (triphenylphosphine) (C830); ruthenium (II) dichloro (tricyclohexylphosphine) (o-isopropoxyphenylmethylene) (C601), and ruthenium (II) (1, 3-bis-(2, 4, 6-trimethylphenyl)-2-imidazolidinylidene) dichloro (phenylmethylene) (bis 3-bromopyridine (C884)).

The transition metal complexes used as catalysts herein can be prepared by several different methods, such as those described by Schwab et al. (1996) J. Am. Chem. Soc. 118:100-110, Scholl et al. (1999) Org. Lett. 6:953-956, Sanford et al. (2001) J. Am. Chem. Soc. 123:749-750, U.S. Pat. No. 5,312,940 and U.S. Pat. No. 5,342,909. Also see U.S. Patent Publication No. 2003/0055262 to Grubbs et al. filed Apr. 16, 2002 for “Group 8 Transition Metal Carbene Complexes as Enantioselective Olefin Metathesis Catalysts”, International Patent Publication No. WO 02/079208 application Ser. No. 10/115,581 to Grubbs, Morgan, Benitez, and Louie, filed Apr. 2, 2002, for “One-Pot Synthesis of Group 8 Transition Metal Carbene Complexes Useful as Olefin Metathesis Catalysts,” commonly assigned herewith to the California Institute of Technology. Preferred synthetic methods are described in International Patent Publication No. WO 03/11455A1 to Grubbs et al. for “Hexacoordinated Ruthenium or Osmium Metal Carbene Metathesis Catalysts,” published Feb. 13, 2003.

Reactants:

The olefinic substrate comprises at least one internal olefin, and may have 2 or more internal olefins. For example, the olefinic substrate may comprise in the range of 2 to about 15, 2 to about 10, or 2 to about 5 internal olefins. By “internal olefin” is meant an olefin wherein each of the olefinic carbons is substituted by at least one non-hydrogen substituent. The non-hydrogen substituents are selected from hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, and functional groups. The internal olefin is therefore at least di-substituted, and may further include additional non-hydrogen substituents such that the internal olefin is tri- or tetra-substituted. Each of the substituents on the internal olefinic carbons may be further substituted as described supra. The internal olefin may be in the Z- or E-configuration. When the olefinic substrate comprises a plurality of internal olefins, the olefinic substrate may comprise a mixture of internal olefins (varying in stereochemistry and/or substituent identity), or may comprise a plurality of identical internal olefins.

The olefinic substrate may be a single compound or a mixture of compounds. The olefinic substrate may be hydrophobic or hydrophilic, although in a preferred embodiment, the olefinic substrate is hydrophobic.

For example, the olefinic substrate may be represented by the formula (R^(I))(R^(II))C═C(R^(III))(R^(IV)), wherein R^(I), R^(II), R^(III), and R^(IV) are independently selected from H, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, and functional groups, provided that at least one of R^(I) or R^(II) and at least one of R^(III) or R^(IV) is other than H. In a preferred embodiment, either R^(I) or R^(II) and either R^(III) or R^(IV) is H, such that the internal olefin is di-substituted.

As another example, the olefinic substrate is an ester of glycerol (a “glyceride”), and has the structure of formula (I)

wherein R^(V), R^(VI), and R^(VII) are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, and functional groups, provided that at least one of R^(V), R^(VI), and R^(VII) is other than hydrogen and comprises an internal olefin. In a preferred embodiment, the olefinic substrate comprises glycerol esterified with 1, 2, or 3 fatty acids, such that the olefinic substrate is a monoacylglycerol, diacylglycerol, or triacylglycerol (i.e., a monoglyceride, diglyceride, or triglyceride, respectively), or a mixture thereof. Each fatty acid-derived fragment of the olefinic substrate may independently be saturated, monounsaturated, or polyunsaturated, and may furthermore derive (or be derivable) from naturally-occurring fatty acids or from synthetic fatty acids. For example, the olefinic substrate may comprise glycerol esterified with one, two, or three fatty acids that are independently selected from CH₃(CH₂)_(n)COOH, where n is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, or 22, palmitoleic acid, vaccenic acid, erucic acid, oleic acid, alpha-linolenic acid, gamma-linolenic acid, linoleic acid, gadoleic acid, arachidonic acid, docosahexaenoic acid (i.e., DHA), eicosapentaenoic acid (i.e., EPA), and CH₃—R^(VIII)—COOH, where R^(VIII) is substituted or unsubstituted C₂-C₂₄ alkenylene. The olefinic substrate may be solid (e.g., a fat) or liquid (e.g., an oil).

Preferred olefinic substrates are seed oils, or are compounds that derive from seed oils.

The olefinic substrate may be a compound or mixture of compounds that is derived from a seed oil or glyceride using any one or combination of methods well known in the chemical arts. Such methods include saponification, esterification, hydrogenation, isomerization, oxidation, and reduction. For example, the olefinic substrate may the carboxylic acid or mixture of carboxylic acids that result from the saponification of a monoacylglycerol, diacylglycerol, triacylglycerol, or mixture thereof. In a preferred embodiment, the olefinic substrate is a fatty acid methyl ester (FAME), i.e., the methyl ester of a carboxylic acid that is derived from a glyceride. Sunflower FAME, safflower FAME, soy FAME (i.e., methyl soyate), and canola FAME are examples of such olefinic substrates. In addition, preferred olefinic substrates include seed oil-derived compounds such as methyl oleate.

Sources of unsaturated esters of glycerol include synthesized oils, natural oils (e.g., seed oils, vegetable oils), animal fats, similar sources and any combinations thereof. Representative examples of vegetable oils include canola oil, rapeseed oil, coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, safflower oil, sesame oil, soybean oil, sunflower oil, linseed oil, palm kernel oil, tung oil, castor oil, combinations of these, and the like. Representative examples of animal fats include lard, tallow, chicken fat, yellow grease, fish oil, combinations of these, and the like. A representative example of a synthesized oil includes tall oil, which is a byproduct of wood pulp manufacture.

The at least one internal olefin is reacted with ethylene, a cross-metathesis partner, in the cross-metathesis reactions of the invention. Ethylene may be provided in the form of a condensed liquid, but in a preferred embodiment, ethylene is provided in the form of a gas. Typically, the pressure of a gaseous cross-metathesis partner over the reaction solution is maintained in a range that has a minimum of about 10 psi, 50 psi, or 80 psi, and a maximum of about 100 psi, 150 psi, 180 psi, 200 psi, 500 psi, 800 psi, or 1000 psi.

Procedures and Reaction Conditions

The components of the reactions of the invention may be combined in any order, and it will be appreciated that the order of combining the reactants may be adjusted as needed. For example, the catalyst may be added to the olefinic substrate, followed by addition of ethylene. As another example, a flask containing the olefinic substrate may be pressurized with ethylene, followed by addition of the catalyst (as, for example, a concentrated solution in a solvent as described herein). The catalyst may be added to the reaction either as a solid or dissolved in a solvent. The catalyst might be added in any quantities and manner effective for the intended results of the reaction. For example in applications where minimization of catalyst's bimolecular decomposition is desired, predetermined amounts of catalyst can be sequentially added to the reaction mixture at predetermined time intervals.

The reactions of the invention may be carried out in a solvent, and any solvent that is inert towards cross-metathesis may be employed. Generally, solvents that may be used in the cross-metathesis reactions include organic, protic, or aqueous solvents, such as aromatic hydrocarbons, chlorinated hydrocarbons, ethers, aliphatic hydrocarbons, alcohols, water, or mixtures thereof. Example solvents include benzene, toluene, p-xylene, methylene chloride, 1,2-dichloroethane, dichlorobenzene, chlorobenzene, tetrahydrofuran, diethylether, pentane, methanol, ethanol, water, or mixtures thereof. In a preferred embodiment, the reactions of the invention are carried out neat, i.e., without the use of a solvent.

It will be appreciated that the temperature at which a cross-metathesis reaction according to the invention is conducted can be adjusted as needed, and may be at least about −78° C., −40° C., −10° C., 0° C., 10° C., 20° C., 25° C., 40° C., 60° C., 100° C., or 150° C. In a preferred embodiment, the reactions are carried out at a temperature of at least about 40° C., and in another preferred embodiment, the reactions are carried out at a temperature of at least about 60° C.

The reactions of the invention are catalyzed by any of the metathesis catalysts that are described supra. The catalyst is typically added to the reaction medium as a solid, but may also be added as a solution wherein the catalyst is dissolved in an appropriate solvent. It will be appreciated that the amount of catalyst that is used (i.e., the “catalyst loading”) in the reaction is dependent upon a variety of factors such as the identity of the reactants (including the identity of the catalyst), and the reaction conditions that are employed. It is therefore understood that catalyst loading may be optimally and independently chosen for each reaction. In general, however, the catalyst will be present in an amount that ranges from a low of about 0.1 ppm, 1 ppm, or 5 ppm, to a high of about 10 ppm, 15 ppm, 25 ppm, 50 ppm, 100 ppm, 200 ppm, 500 ppm, 1000 ppm, or 10,000 ppm relative to the amount of the olefinic substrate. Catalyst loading, when measured in ppm relative to the amount of the olefinic substrate, is calculated using the equation

${{ppm}\mspace{14mu} {catalyst}} = {\frac{{moles}\mspace{14mu} {catalyst}}{{moles}\mspace{14mu} {olefinic}\mspace{14mu} {substrate}}*1,000,000.}$

Alternatively, the amount of catalyst can be measured in terms of mol % relative to the amount of olefinic substrate, using the equation

${{mol}\mspace{14mu} \% \mspace{14mu} {catalyst}} = {\frac{{moles}\mspace{14mu} {catalyst}}{{moles}\mspace{14mu} {olefinic}\mspace{14mu} {substrate}}*100.}$

Thus, the catalyst will generally be present in an amount that ranges from a low of about 0.00001 mol %, 0.0001 mol %, or 0.0005 mol %, to a high of about 0.001 mol %, 0.0015 mol %, 0.0025 mol %, 0.005 mol %, 0.01 mol %, 0.02 mol %, 0.05 mol %, 0.1 mol %, or 1 mol % relative to the olefinic substrate. In a second embodiment of the invention, the olefin metathesis reaction is carried out by contacting, in the presence of a ruthenium alkylidene metathesis catalyst, an olefinic substrate comprised of a mixture of monoglycerides, diglycerides, and triglycerides, with ethylene, under reaction conditions effective to allow cross-metathesis to occur. The olefinic substrate comprises at least one internal olefin, and the metathesis catalyst has the structure of formula (II)

wherein:

m is zero, 1, or 2;

M is Ru or Os;

n1 and n2 are independently selected from zero and 1;

X¹ and X² are anionic ligands;

R¹ and R² are independently selected from H, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl;

L² and L³ are neutral electron donating ligands; and

L¹ is a carbene ligand with the structure of formula (IIIa)

wherein:

Z¹ is —N(Ar¹)(R⁹) and Z² is —N(Ar²)(R^(9A)) or —C(R¹⁰)(R¹¹)(R¹²);

Ar¹ and Ar² are independently aryl substituted with at least one group selected from C₂-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl; and

R⁹, R^(9A), R¹⁰, R¹¹, and R¹² are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, wherein any two of X¹, X², L¹, L², L³, R¹, R², R⁹, R^(9A), R¹⁰, R¹¹, and R¹² may be taken together to form a cycle.

The disclosure for the first embodiment of the invention (e.g., reactants and reaction conditions described supra) also applies for this embodiment.

In a third embodiment of the invention, the olefin metathesis reaction comprises contacting, under reaction conditions effective to prepare a terminal olefin, an olefinic substrate comprising a seed oil or a composition derived from a seed oil and further comprising at least one internal olefin with ethylene in the presence of a ruthenium alkylidene metathesis catalyst comprising an N-heterocyclic carbene ligand, wherein at least about 50% of the metathesis reaction products comprise a terminal olefin and further wherein at least about 50% of the internal olefins initially present in the reaction mixture are converted into terminal olefins. The disclosure for the first embodiment of the invention (e.g., reactants and reaction conditions described supra) also applies for this embodiment.

In a fourth embodiment of the invention, the olefin metathesis reactions comprise contacting, in the presence of a metathesis catalyst, an olefinic substrate comprising at least one internal olefin with ethylene, wherein the metathesis catalyst has the structure of formula (IIA)

wherein:

m is 0, 1, or 2;

n1 and n2 are independently selected from zero and 1;

X^(1A) and X^(2A) are CF₃CO₂;

R¹ and R² are independently selected from H, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl;

L² and L³ are neutral electron donating ligands; and

L^(1A) is an N-heterocyclic carbene ligand.

The disclosure for the first embodiment of the invention (e.g., reactants and reaction conditions described supra) also applies for this embodiment.

In a fifth embodiment of the invention, the olefin metathesis reactions comprise contacting, under reaction conditions effective to prepare a terminal olefin, an olefinic substrate comprising a seed oil or a composition derived from a seed oil and further comprising at least one internal olefin with ethylene, in the presence of a metathesis catalyst, wherein the metathesis catalyst comprises an N-heterocyclic carbene ligand and is present in an amount that is less than about 50 ppm. The disclosure for the first embodiment of the invention (e.g., reactants and reaction conditions described supra) also applies for this embodiment.

It is to be understood that while the invention has been described in conjunction with the preferred specific embodiments thereof, that the description above as well as the examples that follow are intended to illustrate and not limit the scope of the invention. Other aspects, advantages, and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains.

EXAMPLES General Procedures

Low Pressure (<200 Psi) Ethenolyses:

Ethenolyses of research grade methyl oleate were set up under an inert atmosphere in a glove box. As an example reaction procedure, a Fisher-Porter bottle equipped with a stir bar was charged with methyl oleate (>99%) from Nu-Check-Prep (Elysian, Minn.) (15.0 g; 50.6 mmol). A solution of olefin metathesis catalyst of an appropriate concentration was prepared in anhydrous dichloromethane (from Aldrich) and the desired volume of this solution added to the methyl oleate. The head of the Fisher-Porter bottle was equipped with a pressure gauge and a dip-tube was adapted on the bottle. The system was sealed and taken out of the glove box to an ethylene line. The vessel was then purged 3 times with ethylene (Polymer purity 99.9% from Matheson Tri Gas), pressurized to the indicated pressure and placed in an oil bath at the indicated temperature. The reaction was monitored by collecting samples into vials at different reaction times via the dip-tube. Immediately after collecting a sample, the reaction was stopped by adding 1 mL of a 1.0 M isopropanol solution of tris-hydroxymethylphopshine (THMP) to the vial. The samples were then heated for at least 1 hour at 60° C., diluted with 1 mL of distilled water, extracted with 1 mL of hexanes and analyzed by gas chromatography (GC).

High Pressure (>200 Psi) Ethenolyses:

High pressure ethenolyses of research grade methyl were run according to a procedure analogous to that for low pressure ethenolyses, except that a high-pressure stainless steel reactor (Parr) was used in place of the Fisher-Porter bottles.

GC Analytical Method:

The GC analyses were run using a flame ionization detector (FID). The following conditions and equipment were used:

-   Column: Rtx-5, 30 m×0.25 mm (ID)×0.25 m film thickness.     -   Manufacturer: Restek -   GC and column conditions: Injector temperature: 250° C.     -   Detector temperature: 280° C. -   Oven temperature: Starting temperature: 100° C., hold time: 1     minute. -   Ramp rate 10° C./min to 250° C., hold time: 12 minutes. -   Carrier gas: Helium -   Mean gas velocity: 31.3+3.5% cm/sec (calculated) -   Split ratio: ˜50:1

Example 1 Ethenolysis of MO

Ethenolysis reactions using various first and second generation Grubbs catalysts were run according to the general procedure. Data are provided in Table 1.

TABLE 1 Comparison of first and second generation catalysts in ethenolysis of MO.^(a) Con- Se- En- Temp Time version lectivity Yield TOF try Catalyst (° C.) (min) (%)^(b) (%)^(c) (%)^(d) TON^(e) (min⁻¹)^(f) 1 C823 40 120 58 93 54 5,400 45 2 C823 60 30 54 89 48 4,800 160 3 C601 40 30 51 94 48 4,800 160 4 C848 40 120 64 44 28 2,800 23 5 C848 60 <15 64 44 28 2,800 >190 6 C627 40 30 60 33 20 2,000 67 7 C627 60 <15 68 47 32 3,200 >210 ^(a)General conditions: neat MO, 150 psi ethylene, catalyst loading = 100 ppm ^(b)Conversion = 100 − [(final moles of MO) * 100/(initial moles of MO)] ^(c)Selectivity = (moles of ethenolysis products) * 100/(moles of total products) ^(d)Yield = (moles of ethenolysis products) * 100/(initial moles of MO) = Conversion * Selectivity/100 ^(e)TON = Yield * [(moles of MO)/(moles of Cat.)] ^(f)TOF = TON/Time

Example 2 Ethenolysis of MO

Ethenolysis reactions using various catalysts were run according to the general procedure. Data are provided in Table 2.

TABLE 2 Comparison of various catalysts in the ethenolysis of MO Loading Conversion Selectivity Yield TOF Entry Cat. (ppm) Time (min) (%) (%) (%) TON (min⁻¹)  1^(a) C848 100 120 64 44 28 2,800 23  2^(b) C848 100 <15 64 44 28 2,800 >190  3^(a) C627 100 30 60 33 20 2,000 67  4^(b) C627 100 <15 68 47 32 3,200 >210  5^(a) C782 100 <15 38 71 27 2,700 >180  6^(b) C782 100 <15 53 60 32 3,200 >210  7^(a) C712 100 30 70 56 39 3,900 130  8^(b) C712 100 <15 79 71 56 5,600 >373  9^(a) C712 35 <15 69 57 39 11,000 >733 10^(c) C712 100 360 87 80 70 7,000 19 11^(c) C712 25 360 51 63 32 12,800 36 12^(a) C933 100 60 69 55 38 3,800 63 13^(a) C933 10 60 61 36 22 22,000 367 14^(a) C866 100 30 49 94 46 4,600 150 15^(b) C866 100 <15 43 88 38 3,800 >250 16^(c) C866 100 <30 39 92 36 3,600 >120 17^(c) C866 500 <15 86 94 81 1,620 >110 18^(d) C697 100 1260 66 53 35 3,560 <3 19^(e) C697 100 390 79 72 57 5,710 15 20^(f) C697 100 120 81 67 54 5,410 45 21^(a) C785 100 1380 58 55 32 3,200 <3 22^(b) C785 100 180 78 73 57 5,640 31 23^(b) C859 100 240 77 66 51 5,200 22 24^(g) C859 100 30 76 61 46 4,680 156 25^(a) C859 100 1200 71 59 42 4,200 <4 26^(a) C879 100 390 51 69 35 3,570 9 27^(b) C879 100 240 59 90 53 5,370 22 28^(b) C965-p 100 30 58 45 26 2,500 84 29^(b) C824 100 30 35 86 30 2,990 100 30^(a) C606 100 1,320 61 92 56 5,600 4 31^(a) C606 50 1,200 61 93 57 11,400 10 32^(a) C578 100 <30 73 73 53 5,300 >177 33^(a) C578 35 60 75 75 56 16,000 267 34^(a) C578 10 <30 42 83 35 35,000 >1,167 35^(a) C646 100 360 46 94 43 4,200 12 36^(a) C838 100 1320 60 90 54 5,440 4 37^(g) C577 100 300 74 84 62 6,330 21 38^(b) C577 100 1380 67 90 60 6,150 <5 39^(a) C767-m 100 30 37 32 12 1,150 38 40^(a) C811 100 15 62 34 21 2,100 140 41^(a) C916 100 15 65 45 29 2,900 194 42^(b) C827 100 120 75 64 48 4,790 40 ^(a)neat MO; 40° C.; 150 psi ethylene. ^(b)neat MO; 60° C.; 150 psi ethylene. ^(c)neat MO; 25° C.; 800 psi ethylene. ^(d)neat MO; 40° C.; 180 psi ethylene. ^(e)neat MO; 60° C.; 180 psi ethylene. ^(f)neat MO; 80° C.; 180 psi ethylene. ^(g)neat MO; 80° C.; 150 psi ethylene

Example 3 Ethenolysis of MO

Ethenolysis reactions using various catalysts were run according to the general procedure. Data are provided in Table 3.

TABLE 3 Comparison of C606 and C578 to C848 and C627 in ethenolysis of MO^(a) Loading Conversion Selectivity Yield TOF Entry Cat. (ppm) Time (min) (%) (%) (%) TON (min⁻¹) 1 C848 100 120 64 44 28 2,800 23 2 C627 100 30 60 33 20 2,000 67 3 C606 100 1,320 61 92 56 5,600 4 4 C606 50 1,200 61 93 57 11,400 10 5 C578 100 <30 73 73 53 5,300 >177 6 C578 35 60 75 75 56 16,000 267 7 C578 10 <30 42 83 35 35,000 >1,167 ^(a)Conditions: neat MO; 40° C.; 150 psi ethylene.

Example 4 Ethenolysis of Pure Methyl Oleate with 2^(Nd) Generation Catalysts

As in the reaction shown below, methyl oleate was reacted with ethylene and 100 ppm of catalyst C₆₂₇ according to the general procedure given above. The results are illustrated in the graph shown in FIG. 1. 

What is claimed is:
 1. A method for synthesizing a metathesis reaction product having a terminal olefin, the method comprising contacting, in the presence of a metathesis catalyst, an olefinic substrate comprised of at least one internal olefin with ethylene, wherein the catalyst is present in an amount that is less than about 1000 ppm relative to the amount of the olefinic substrate, and wherein the metathesis catalyst has the structure of formula (II):

wherein: M is Ru or Os; m is zero, 1, or 2; n1 and n2 are independently selected from zero and 1; X¹ and X² are anionic ligands; R¹ and R² are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl; L² and L³ are independently neutral electron donating ligands; L¹ is a carbene ligand with the structure of formula (IIIb):

wherein Ar¹ is an aryl substituted with at least one group selected from the group consisting of C₂-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl; a is an optional double bond; and R¹⁰, R¹¹, R¹³, R¹⁴, R¹⁵ and R¹⁶ are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, wherein any two or more of Ar¹, R¹⁰, R¹¹, R¹³, R¹⁴, R¹⁵, and R¹⁶ may be taken together to form a cyclic group, and provided that R¹⁴ and R¹⁶ are not present if a is present.
 2. The method of claim 1, wherein Ar¹ has the structure of formula (VIIa):

wherein

represents the attachment point to N in formula (IIIb), R¹⁷ and R¹⁸ are independently selected from the group consisting of C₂-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl, and R¹⁹, R²⁰, and R²¹ are independently selected from the group consisting of hydrogen, C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₂ aryl, C₆-C₁₂ aralkyl, and C₆-C₁₂ alkaryl.
 3. The method of claim 2, wherein R¹⁹, R²⁰, and R²¹ are hydrogen such that Ar¹ has the structure of formula (VIIb):


4. The method of claim 1, wherein the olefinic substrate is selected from the group consisting of seed oils, alkyl esters of unsaturated fatty acids, and aryl esters of unsaturated fatty acids.
 5. The method of claim 1, wherein the olefinic substrate comprises a mixture of internal olefins selected from the group consisting of monoacylglycerols, diacylglycerols, triacylglycerols, and combinations thereof.
 6. The method of claim 1, wherein the olefinic substrate is of the formula (R^(I))(R^(II))C═C(R^(III))(R^(IV)), wherein R^(I), R^(II), R^(III), and R^(IV) are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, and functional groups, provided that at least one of R^(I) or R^(II) and at least one of R^(III) or R^(IV) is other than hydrogen. 